Different contribution of BH3-only proteins and caspases to doxorubicin-induced apoptosis in p53-deficient leukemia cells

Nuria López-Royuela, Patricia Pérez-Galán, Patricia Galán-Malo, Victor J. Yuste, Alberto Anel, Santos A. Susín, Javier Naval, Isabel Marzo

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25 Citations (Scopus)

Abstract

Bcl-2 family proteins are key regulators of the intrinsic apoptotic pathway, either facilitating (Bax, Bak, BH3-only) or inhibiting (Bcl-2, Bcl-xL, Mcl-1, A1) mitochondrial release of apoptogenic factors. The role of caspases in this process is a matter of controversy. We have analyzed the relative contribution of caspases and Bcl-2 family of proteins in the induction phase of apoptosis triggered by doxorubicin in two p53-deficient leukemia cell lines, Jurkat and U937. First, we have found that caspases are dispensable for the induction phase of doxorubicin-induced apoptosis in both cell lines but they are needed to speed up the execution phase in Jurkat cells, not expressing Bax. Thus, down-regulation of Bak expression by siRNA significantly prevented doxorubicin-induced apoptosis in Jurkat but not in U937 cells. Reduction of Mcl-1 protein levels with siRNA increased sensitivity to apoptosis in both cell lines. Moreover, our results indicate that the contribution of BH3-only proteins to apoptosis is cell line specific. In Jurkat cells simultaneous silencing of Bim and PUMA was necessary to reduce doxorubicin-induced apoptosis. In U937 cells silencing of Bim or Noxa reduced sensitivity to doxorubicin. Immunoprecipitation experiments discarded an interaction between Mcl-1 and Bak in both cell lines and underscored the role of Bim and PUMA as mediators of Bax/Bak activation. © 2010 Elsevier Inc.
Original languageEnglish
Pages (from-to)1746-1758
JournalBiochemical Pharmacology
Volume79
DOIs
Publication statusPublished - 1 Jan 2010

Keywords

  • AIF
  • BH3-only proteins
  • Bcl-2 family proteins
  • Caspases
  • Doxorubicin

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